The present invention relates to a coaxial transmission, especially hollow shaft transmission for industrial drive engineering, having high power density, with a drive element, with an element and with an output element, a step-up and a transfer of a drive torque between the drive element and output element taking place via a plurality of radially movable toothed segments, the at least one toothed segment having a supporting element in the range of action with respect to the drive element.
Conventional transmissions are known and obtainable commercially in any form and version.
Essentially three different technologies of transmissions are employed commercially. On the one hand, epicyclic transmissions are known commercially, in which, for example within a ring wheel, one or more planet wheels are provided coaxially, by means of a mostly centrally arranged sunwheel, with the transfer of a torque to a planet wheel carrier or an output element.
In planetary or epicyclic transmissions of this type, they cannot run at high transfer speeds and, because generally there are only very small possible hollow shaft diameters, they cannot transfer high torques. Moreover, transmissions of this type suffer from low rigidity and low robustness and have a low overload capacity.
Furthermore, there is the disadvantage that, especially in case of high drive-side rotational speeds, a step-up or a step-up ratio is restricted.
Furthermore, eccentric transmissions are known in which, mostly, a planet wheel is provided within an internally toothed ring wheel for transferring the torques and for effecting step-ups.
The disadvantage of eccentric transmissions is that these require high separating forces in very large bearing elements, especially in hollow shaft versions, and are suitable only for hollow shaft versions having a smaller diameter. Even here, these eccentric transmissions have low overload capacities and low robustnesses.
Moreover, the step-up ranges are restricted to about i=30 to i=100, and only at low drive rotational speeds. At higher drive rotational speeds, eccentric transmissions of this type are subject to high wear and therefore have a short service life, which is undesirable.
Moreover, eccentric transmissions of this type have high frictional losses and therefore low efficiencies when clutches or the like follow eccentric transmissions in order to shift eccentric output movement to a centric movement. Efficiency of the eccentric transmission is therefore very low.
Especially at high rotational speeds, serious vibration problems arise which are likewise undesirable.
Furthermore, harmonic drive transmissions are known, which, indeed, can also be implemented as hollow shaft transmissions, there being arranged between the drive element of mostly oval design and an internally toothed ring wheel a flexible spline, as it is known, which is designed to be soft and resilient and which transfers the corresponding torque between the drive and ring wheel and allows a step-up.
The flexible spline, as it is known, is subject to permanent loads and often fails under high torques. Moreover, the flexible spline does not have overload capacity and often quickly breaks off when torques are too high. Furthermore, the harmonic drive transmission has poor efficiency and low torsional rigidity.
DE 31 21 64 represents the prior art closest to the present invention. Said document relates to a self-locking shift transmission in which a plurality of arms, which are arranged in a stellate fashion around a shaft, are mounted with their inner ends eccentrically on the shaft. The arms are designed as two-armed levers, their centers of rotation are guided in a crossed fashion and their inner ends rest independently of one another on the driving eccentric, such that the outer ends perform a connecting rod movement. Here, said ends engage in succession into the gearwheel and drive the latter in the opposite direction to the rotation of the driveshaft. The contact surfaces are widened in relation to the tooth roots. However, said contact surfaces are fixedly connected, not connected loosely or in a joint-like manner, to the tooth or toothed wheel.
The object on which the present invention is based, therefore, is to provide a coaxial transmission of the type initially mentioned, which eliminates said disadvantages of the hitherto known coaxial transmissions, epicyclic transmissions, eccentric transmissions and harmonic drive transmissions, while force transfer between the drive element and toothed segment is to be improved markedly with the transfer of very high forces.
Moreover, the coaxial transmission is to have very high compactness and complexity, with the smallest possible installation space and lowest possible weight at a certain power rating.
The fact that the supporting element is movable, in particular in an articulated manner, in a joint-like manner, pivotably connecting or supported slidably, with respect to a basic body of the respective toothed segment and that the supporting segments together result in a segmented mounting leads to the achievement of this object.